Answer: n+457
====================================================
Explanation:
The variable n is a placeholder for a number. Specifically some positive number. Let's say that n = 50. This means Eric biked 50 miles last year.
That would mean in total he biked 50+457 = 507 miles overall over the two years.
Since we don't know what n is, we don't replace it with 50. So we just keep n as it is. We would keep it as n+457
Once, or if, we find out the value of n, then we can replace that letter with that number.
